Meat packing plants generally include an area called a kill floor where the animals are slaughtered, sectioned and the hides, organs and the like are removed. The meat sections are then transferred to a cooling area where the meat is initially chilled and thereafter held pending further processing. It will be appreciated that the temperature of the kill floor is substantially higher than that of the cooler. While prior art packing plants were provided with various types of automatic doors between these areas, the latter were required to be opened frequently to permit the passage of meat from the kill floor to the cooler. As a result, there was a substantial interchange of cool air from the cooler and warm air from the kill floor. This not only increased the refrigeration requirements of the cooler but caused undesirable sweating and condensation to occur on the meat.